Diffusion-illuminated drawing board



' w. A. MEHESS ET AL 3,356,839

DIFFUSION-ILLUMINATED DRAWING BOARD Dec. 5, 1967 Filed July 26, 1965 JA/VEA/IbQg, mun w A M EHESS, OSE-PH C. M NEO, I

mn/ 7%m United States Patent 3,356,839 DIFFUSION-ILLUMINATED DRAWING BOARD William A. Mehess, Panorama City, Calif., and Joseph C. Mineo, 6735 Shoup Ave., Canoga Park, Calif. 91303;

said Mehess assignor to said Mineo Filed July 26, 1965, Ser. No. 474,761 1 Claim. (Cl. 2406.4)

ABSTRACT OF THE DISCLOSURE A drawing and tracing board with self-contained illumination under the drawing surface, the board being made of translucent and light diffusing plastic, with bulbs for illumination received in recesses within the board under the drawing surface, and with batteries and wiring accommodated in a frame structure.

This invention relates generally to portable illuminated drawing boards, but it relates more particularly to such a drawing board in which effective illumination from small batteries is achieved by means of a plurality of light bulbs distributed through the clear interior material of the drawing panel so as to produce a maximum of intensity and uniformity of distribution of light at the drawing surfaces a It frequently happens-that it is desirable or important to make drawings or notes in a laboratory or lecture hall which must be dark for reasons connected with the work being done. Various illuminated drawing boards and lecterns have been proposed, but most of these require a power connection to llO-Volt electrical distribution receptacle. Such drawing boards are not relevant to the present invention, since they are not really portable and independent of an electrical outlet.

Heretofore, battery-illuminated drawing boards have been impractical and unsatisfactory because, if light enough to be portable in a single piece, they have failed to produce sufliciently uniform and intense illumination over the entire drawing surface. For example, some have been comprised of an upper glass plate and a lower reflective plate with illumination projected in between. Such drawing boards are not only extremely fragile and prone to breakage, but the low power illumination which can be obtained from readily portable batteries and bulbs produces only a bright spot or two in the vicinity-of the bulb, at the surface of the glass, wit-h illumination falling off rapidly into darkness in other parts of the glass plate drawing surface.

It is the primary object of the present invention to provide an extremely rugged and almost unbreakable portable drawing board, which is capable of providing illumination over the entire drawing surface from within.

It is an associated major object of the invention to produce such illumination with the degree of uniformity not heretofore known, and with a minimum of variation in light intensity from portions of the drawing surface in the immediate vicinity of the illuminating bulbs, and those portions most remotely located from those bulbs.

It is still another purpose of this invention to provide a portable illuminated drawing board in which the housings which enclose batteries, wiring, bulb sockets, and switch means, serve the extra function of protecting the drawing panel from damage around its periphery.

The foregoing and other objects and advantages of the invention are achieved by means which will be best understood from a reading of the following description of one preferred specific embodiment, taken in connection with the accompanying drawings, in which:

FIGURE 1 is a perspective view of a drawing board constructed according to the present invention;

FIGURE 2 is a rear elevational view of the drawing board of FIGURE 1;

FIGURE 3 is a perspective view of the drawing board of FIGURE 1, in substantially the same position, but with the right socket housing and the battery housing disassembled to reveal internal construction;

FIGURE 4 is a detailed sectional view taken at a vertical plane indicated by the numerals 4-4 in FIGURE 3, to show a transverse section of the left socket housing, and the mounting thereon of a socket and bulb; and

FIGURE 5 is a sectional detailed view taken at the vertical plane indicated by the numerals 5-5 in FIG- URE 3, and showing the manner in which the left socket housing is screwed to the left side edge of the drawing panel.

In FIGURE 1, a drawing board indicated generally by the numeral 10- is seen to be comprised principally of a relatively massive panel 11, to the side edges of which are attached right and left side socket housings 12 and 13.

A battery housing 14 covers the upper portion of the upper surface of panel 11, and overlaps the socket housings 12 and 13.

Various housings 12, 13, and 14 are all screwed directly to the panel 11t he socket housings 12 and 13 by screws 12a and 13a visible in FIGURES 3 and 1, respectively, and the battery housing being screwed by screws 14a to the rear end of panel 11 as seen in FIGURE 2.

It will be seen that the housings 12, 13, and 14 may be readily unscrewed for battery or bulb replacement as illustrated in the partially disassembled perspective view of FIGURE 3.

Also, the lifting away of the battery housing 14 in FIG- URE 3 reveals that the batteries 15 are snapped into the conventional type of spring contacts in battery holders 16 and 17, which latter are screwed directly to the upper face of the panel 11. A suitable electric switch 18 is fastened to the interior of the housing 14 and is operated by means of projecting switch toggle 18a fro-m the rear of the battery housing 14 as seen in FIGURE 2.

The wiring 19 which interconnects the switch 18, the batteries 15, and illumination means to be described hereinafter, is seen to be sufliciently loose to permit partial disassembly for servicing.

Also, it will be noted that the manner in which the battery housing 14 overlaps the right and left socket housings 12 and 13 makes it possible for the wiring to be entirely enclosed by these housings.

The illumination of the drawing panel 11 is accomplished by means best understood from FIGURES 3 and 4. The removal of right socket housing 12 reveals that it is a long rectangular trough, which mates with the thickness of the panel 11 as seen in FIGURE 4. Within its hollow, rectangular-cross-section interior, a number of bulb sockets 21 are mounted so as to project directly toward the adjacent edge of panel 11, with the exposed portion of a light bulb 22 beginning at approximately the panel edge.

Light bulb 22 is received into the interior of a bulb cavity 23 which is only slightly larger than sufficient to closely accommodate the bulb 22.

It will be understood that the wiring 19 extends from the batteries 15 to all of the bulb sockets 21, being provided with entrance to the socket housings 12 and 13 through small wiring openings 12b and 13b seen in FIG- URE 3. Operation of the switch 18 simultaneously illuminates all of the bulbs 22, which are spaced along the op posite side edges of panel 11, and are mounted in a series of duplicate sockets 21 and accommodated within panel 11 in a series of duplicate bulb cavities 23.

The attachment of the socket housings 12 and 13 to the side edges of the panel 11 is by means of the screws 1311 which pass through spacers 24 and are threadably re ceived in threaded bores 25 in the side edges of panel 11.

It is an important feature of the invention that the panel 11 is made of clear transparent material, preferably a nonshattering plastic of good light conductivity such as that known commercially as Lucite. Obviously, other methyl methacrylate plastics and the like may be employed. Light from bulbs 23 is thus distributed throughout the interior of panel 11.

The bottom surface of the panel 11 is made reflective as indicated at 30, by some suitable means such as a coating with mirror silver. The coating should be opaque so that no light escapes from the bottom surface of panel 11, and all is reflected upwardly.

The upper, or drawing surface 31, of panel 11 should be formed to be translucent and diffusing, and not transparent, so as to minimize spots of excessive brilliance, and achieve a softly diffused pool of light over the upper surface 31.

Preferably, the sanded upper drawing surface is then covered with a coating to make it smooth and hard, and to avoid any irregularities produced by sanding.

It will be seen from the foregoing description of one preferred specific embodiment that we have provided a portable illuminated drawing board construction which combines both superior illumination and superior ruggedness by virtue of the double function of the side socket housings 12 and 13 and the battery housing 14. However, it will be understood that the invention is not limited to the details of the specific embodiment illustrated, but is intended to comprehend any variation, improvement, or simplification which falls within the scope of the appended claim.

Having described the invention, what is claimed as new in support of Letters Patent is:

A portable illuminated drawing board comprising:

a drawing board panel of clear transparent material except for the drawing surface, which is constructed to be translucent and diffusing for light transmitted through the clear interior of said panel;

means forming a reflective lower surface on the side of said panel opposite said drawing surface;

hollow socket housings attached to at least two opposite edges of said panel;

a plurality of light bulb sockets spaced along the interior of said socket housings;

light bulbs mounted in said sockets and received into bore holes into the adjacent edge walls of said panel to permit the transmission of light from said bulbs directly into the transparent interior of said panel;

battery holder means attached to a part of one surface of said panel, and battery means adapted to energize said bulbs mounted therein;

battery housing means received over said battery holders and batteries and extending into overlapping contact with parts of each of said socket housings;

switch means mounted in said battery housing and providing switch control from the exterior thereof; and

wiring between said battery means, said switch means, and said socket for the controlled operation of said bulbs, said wiring being concealed within said battery housing and passing therefrom through the interior of said socket housings to said sockets.

References Cited UNITED STATES PATENTS 2,347,665 5/ 1944 Christensen 2406.4 2,358,203 9/1944 Best 2401 2,898,880 8/1959 Newton 2401 3,004,140 10/ 1961 Gomes 240-646 3,023,304 2/ 1962 Peterson 2401 NORTON ANSHER, Primary Examiner.

JOSEPH F. PETERS, Assistant Examiner, 

